


Once Upon a Falling Star

by GrandestBlood



Series: Rapid Writing Prompts [2]
Category: Supernatural
Genre: Alternate Timelines, Alternate Universe - Canon Divergence, Alternate Universe - Post-Apocalypse, M/M, Post-Apocalypse
Language: English
Status: In-Progress
Published: 2020-08-04
Updated: 2020-08-11
Packaged: 2021-03-05 20:07:48
Rating: General Audiences
Warnings: Major Character Death
Chapters: 2
Words: 3,380
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25701085
Author URL: https://archiveofourown.org/users/GrandestBlood/pseuds/GrandestBlood
Summary: Alternate outcome for season 5's Endverse where Castiel never lost his grace but he was tricked to retreat back to heaven with the other angels, leaving Dean behind in the refugee camp.Prompt for this was: The world has ended 500 years ago. You finally went back to Earth and discovered a voice message. You learn a shocking secret about 500 years ago.
Relationships: Castiel/Dean Winchester
Series: Rapid Writing Prompts [2]
Series URL: https://archiveofourown.org/series/1863829
Comments: 4
Kudos: 21





	1. Not Too Late

**Author's Note:**

> I'll probably edit this again later.

Half a millennium was not a very long time for a multidimensional wavelength of celestial intent – or an angel as common human language liked to call them. But it was a long time to close off Heaven so that no entity could get in nor out. When the apocalypse came on earth and Castiel refused to leave, Hannah made sure to drag him off, wings and halo intact even if it involved tricking him with a spell to trap him in a crystal that made him sleep everything away.

Now, Castiel was awoken by a voice and not just any voice but the voice of the righteous man who taught him free will and human emotions all those many years ago. It took him a while to break out of the crystal but after he had done it and realized how much time had passed, he knew it was already too late to look for that voice.

Human life was bound to be lived short and meaningful after all, if there was really any meaning left to it after it was manipulated by heaven and hell all along. But even so, despite the surety of it, Castiel wanted to see what was left of the righteous man; of his best friend; of the man he once loved.

So he rebelled against all of heaven’s angels again, killed his brothers and sisters who stood in his path. He slit their throats and stole their grace to use them to reverse the spell that kept heaven locked up. And then he came down on earth, all fury and sorrow compressed in a tangle of fiery wings like a comet hitting the crust and destroying the immediate vicinity; not that there was much to destroy because earth was a wasteland.

Five hundred years had passed since archangel Michael refused to help humanity and Lucifer reigned free along with a plague that made people eat each other’s souls. It was horrifying to imagine how Dean possibly went through that alone. And yes, Castiel knew the righteous man had to be alone for his brother was lost long before Castiel was trapped by Hannah.

Sam gave in to Lucifer and got possessed before heaven went mad and quit their game. Castiel never saw his brother possessing the good friend he knew about but imagining how it was like for Dean while Castiel was not there – while Dean probably thought his only friend left alive left him willingly – made his already foul mood get even nastier. It was maybe a good thing that earth had no more life left on it so there was no one to take the brunt of his anger when he lashed out on his surroundings. There was only a burnt land littered with bones and decay, a sky so gray that clouds were more like smoke. Even the smell of it was deprived of life.

Castiel pushed on, scanning what used to be camp Chitaqua – the last refugee camp that Castiel knew Dean lived in before he was deceived and forced in a deep sleep. He used his inhuman senses to make his search more efficient and his grace seeped in to every molecule around him, into the dimensions of time, space and memories.

To the far right of where he stood was a ramshackle makeshift tent, or at least that was the most generous description he could give to a collection of tattered cloth and sticks that looked like they used to be able to hold themselves up together. He searched through it and among the broken bottles of liquor was a voice recorder. It was a useless old junk with batteries that leaked inside, rusted and broken. But that did not matter because Castiel had his grace in him and with it comes his abilities. He reversed its time and made it look as though it was brand new. Then he hit the play button.

“Cas, I don’t know if you can hear me and that’s why I’m recording this, you know, instead of praying,” it was Dean’s voice that came out of the last recording from the device and it confirmed Castiel’s suspicions that his friend thought he left him. “I just want to say goodbye.”

Castiel’s breathe hitched and he stopped breathing at all. He did not need air to live but it was a habit he kept doing around humans. Now that he was utterly alone, it seemed that his physical body just automatically stopped pretending it was anything but a monster.

“We have nowhere left to go, Lucifer had gotten to us,” the recording continued and Castiel waited in silence for the next words to come. “I shouldn’t have fought with you or Sam. I’m sorry.”

Dean’s voice cracked from the record and he started sobbing. It was a few seconds before he continued and Castiel almost thought he wouldn’t, that Dean died right there. “I’m sorry I was so afraid to lose you that I never even thought about having you.”

Oh.

So it was that kind of goodbye.

And suddenly, Castiel felt weak like all the anger he felt after waking up five hundred years into the future with all his loved ones dead left him. He wanted this. He wanted to see what was left of Dean and now he had it. But the words he was hearing – he never wanted to hear them like this. There were parting words you could hear from phone and they would be fine and there were words you must hear upfront or they were not enough. And then there were goodbyes that will never feel like a goodbye because there was never a chance to even say hello.

“I’m sorry I was scared to love you.”

And there they were, the words Castiel feared to hear from a disembodied voice. Because it was unfair to hear them from a dead man. There was a dead silence from the recording before Castiel hears the loud bang of a gun getting fired too close to the receiver to be fired at someone else other than the once holding it.

Castiel dropped on his knees and buried the recorder. It was the only thing he had left of Dean. And so he mourned. But no for so long. Because he swore to himself he will not let the apocalypse come true without giving a fighting chance to the man he loved.

The moon still shone on the desolated earth by nighttime and Castiel enjoyed the view of it before he disappeared with a sound of thunderous wings taking flight. If he must destroy half a millennium of history to change the fate of the man that changed him, then so be it.

Heaven hath no fury than a fallen angel scorned.


	2. Da Capo

**Summary for the Chapter:**

> One of them seeks out answers the other did not care about finding. He just wanted to be back when he felt he belonged.

Castiel fought the handful who came to look for him, asking him to come back to Heaven. After that first set of angels gave up squaring up with him, a new batch of diplomatic ones came in wanting to talk. He did not kill them right away. Instead, he allowed them a bit before he ran out of patience. But it was not mercy; he simply needed them alive first.

“Please, don’t do this!” Hael groveled at his feet even as she gasped and crawled away from him, her wings broken and burned from the fight that Castiel brought to her with retribution. She still wheezed and tried to save herself even if it looked obvious that she never stood a chance. As an angel, Hael was an artist that created memorable etchings on Earth. She was no warrior unlike Castiel who led his garrison into battle with demons and fought to retrieve Dean Winchester from Hell.

Dean.

Yes, he was the reason why.

But Hael would not understand so Castiel did not see the point in telling her more about his reasons. And he only needed her grace to gain the strength he will need to go half a millennium back in time.

“Why?” Hael sobbed as she pulled herself up a little more, her legs unable to move as Castiel had broken them easily with his mind. “Are you really going to sacrifice what’s left in this world in the name of one dead man?”

When Hael came to talk with no will to fight at all, Castiel thought he’d try to listen to her stories of the apocalypse out of curiosity. Hael retreated back to Heaven but she never stopped looking down and watching earth. She fancied earth, just not the humans. She loved the land that nourished the animals she cared about, loved the way the morning dew smelled like and she loved how birds sang in the morning and crickets come past the dusk. Hael occasionally saw humanity when she checked how earth was doing during the apocalypse and she hated that each time, what she loved became more and more destroyed as the war and plague went on. But in the end, she did not stop it.

“Don’t you dare speak of Dean,” he said, finally stepping on her head and half-tempted to do to it what he did to her legs. But that won’t kill her. Hael’s vessel will just get too useless to move and with not enough grace, she won’t be able to heal it. She will need a new one but there were no humans left to give her shelter in their bodies. If Castiel let her go, she will just return to Heaven as immaterial as the day she was created. Then she will lead more angels to him in vengeance and hiding away from them so he could pick his battles and outwit them to win will prove to be useless. He won’t let that happen.

Castiel caught her face and she struggled and tried to claw at him as he forced her to look at him in the eyes. Then Castiel slit her throat and peered inside her, at her true form, at the angel beyond the cage of flesh. Hael was beautiful and any human who saw her will get their eyes burned from a glimpse at her grace but they would give praise and thank the moment they thought they saw their salvation. But Castiel was no human and he had no soul and his eyes burned as much as hers. He saw the eyes from her wings, weeping and bleeding in the way only angels could do. Angels did not bleed with blood but the entirety of their existence.

From Hael’s eyes, Castiel saw what she saw – the Grand Canyon from before the apocalypse and the fall of humanity during he slept. Castiel swallowed her grace and he felt what she felt including the apathy she bore for humans as their souls became corrupted so they could become demons. It felt disgusting as it surrounded Castiel’s own grace when he remembered how Dean felt when he feared becoming what he hunted in the dead of the night. But Castiel devoured all the memories until Hael bled dry and could bleed no more. When he was done, he dropped her on the wasteland that he stood on. Devoid of celestial energy, Hael started to bleed with blood from the wound on her neck and Castiel thought it was appropriate for her to die a human death after she turned a blind eye on the suffering and devastation she saw on Earth..

“Castiel, stop.”

And that voice, Castiel remembered he heard again and again telling him to stop loving humanity more than he could love God.

“Naomi,” Castiel said in lieu of greeting.

“I will not tell you to turn back like Hael did,” Naomi said, stepping back as Castiel let the hilt of his angel blade fall into his hand from inside his sleeve. “But I will not fight you, either.”

Castiel remembered Naomi from the times he was too out of control, always the faulty soldier Heaven could never truly transform into an obedient doll. She taught him lessons after lessons of why he must follow and forget about his arguments, forget about asking for reasons why he should not help Dean or Sam. Naomi was the one who disciplined him once again when he finally decided to take the Winchester’s side and was exorcised for it.

“What do you want?”

“I should ask you that but we both know the answer already,” she said, watching him kick Hael to the side who was slowly dying. “If this world has no more meaning to you because Dean Winchester is gone, then just leave. I’m not stopping you but let Hael go.”

“You don’t have to tell me, I never planned to take her,” he said, bringing his blade up and marching on towards her. “But you? I’ve always wanted to take you out.”

And if Castiel felt like taking a long time breaking Naomi’s wings before absorbing her existence from her bleeding grace, Castiel will tell himself later that it was necessary to complete his power so he could stay strong once he was back in time. But in reality, Castiel knew he would enjoy taking her apart and leaving her alive but empty right after. Naomi definitely enjoyed doing that to him five hundred years ago and beyond. It was always a good idea to return the favor.

“If you kill me,” Naomi started, still not bringing her blade out. “You will not be able to leave at all.”

“I am powered by the grace of all the angels who sought me out,” he said, as he circled Naomi like a wolf seizing up his prey. “You can do nothing to me, Naomi. And that’s why you wish for me to disappear.”

“You need me to find who can help you,” Naomi said, raising her wings defensively. If she thought appearing harmless was going to sway Castiel’s resolve, she was being delusional. “Michael only allows a handful of angels to see him at a time.”

“And why would I believe Michael does not want me dead?”

“Please, Castiel. Just let me bring you to him. He wanted to help you.”

Castiel laughed mirthlessly and twirled his blade around his wrist. “If he wanted to help, he could have done that sooner.”

“He tried preserving humanity in your absence.”

The last word stung Castiel as like a scorpion’s tail. Naomi said it as if it was his fault that he was not there when earth saw its last rays of hope. He did not owe her any explanation but Cas felt the need to scream that he never wanted to leave his friends behind. But whatever words Cas wanted to say to Sam, Dean, Bobby, Ellen or Jo – he kept them close to his heart and away from his mouth. An angel who felt nothing for humanity deserved no emotion from him.

“Once Lucifer thought he won, Michael tricked him to end the apocalypse,” Naomi continued, relaxing a bit while Cas returned his blade inside his sleeve. “It was the only way with Dean refusing to give him a vessel.”

Cas grinded his teeth. Would he forgive Michael for letting the apocalypse happen? Should he give him a chance? Is Michael worth his trust?

“Fine, then lead the way.”

“Thank you, you will not regret this.”

Castiel thought he would but if he did, when he did, he knew he could just see inside Naomi and maybe Michael too. At least he must see the archangel with his own eyes and the easiest way to find out where he could be hiding was to follow Naomi temporarily and deal with her later. She stretched out her with her palm up invitingly and he took it.

When Cas opened his eyes next, he saw that he and Naomi stood inside what looked like a motel room from then the world was still intact. Castiel knew from the smell of the ozone alone that it was Heaven despite the decoration resembling the motels the Winchesters used throughout their lives. At the back of the room was a kitchenette where Castiel could see the archangel stood still, waiting for him. It was very typical of Michael to be hiding out somewhere so he did not have to see the chaos outside even after ending the apocalypse like a hero from legends. Killing Lucifer was not ideal for Michael, hurting his brothers and sisters never was even if he thought he was doing it for God. He just did not have the guts to question it enough. Castiel also felt the same way once before everything stopped mattering to him.

“Castiel,” Michael called, his current vessel not recognizable to Castiel. He motioned like he would embrace the seraph but Castiel brought out his blade and both Naomi and Michael stepped away from him. “You’re very unfriendly for someone who needs something from me.”

“I don’t even know what you think I need.”

“What you’re trying to do, brother, it might kill you,” Gabriel said from a safe distance from Castiel. “Going back through time and staying there to make a significant change? Even grace from a thousand angels will not be enough. You will run out of energy eventually.”

Castiel felt like protesting because even if he had not reached a thousand yet, he felt his grace eating up all of the others’ and being fueled infinitely by all of them. Castiel, at the moment, was as strong as an army of angels even on his own. He just didn’t know how he’d fare against an archangel because he never absorbed one.

“But you don’t have to if you use mine.”

“There’s no way you’ll bleed for me without something in return.”

“Castiel, look around you,” Michael said with a sigh as he pulled on his hair in frustration. “I did everything to find them. But their souls are not in Heaven. I also combed through Hell. Neither Sam nor Dean Winchester are in this world. Their souls are just gone.”

And that was how the motel made sense to Cas. It was not made to look like one. It was one of the many where Dean alone stayed and survived a day. Whatever happened in that particular room, Castiel did not know but it was part of Dean’s Heaven. Michael looked everywhere for what was left of the Winchesters and when he failed, he locked himself inside Dean’s Heaven to wait. But he got tired of waiting. Castiel himself did not want to see this much less lock himself inside the ghost of Dean’s memories. He felt that Dean was gone from the lack of the previously insistent longing he felt even while he slept. He did not need more proof of it.

“I did what my father wanted me to do but there’s no proof it was the right thing to do – not even the wrecked souls I sacrificed for him.”

“This is a trick, you just want to kill me. And Naomi set you up for it.”

“Naomi has no command over me, Castiel. I am an archangel, “Michael raised his voice, “You must go back in time and seek out answers. I have a spell that will send your grace back to your past self. This is faster and it will stop more angels from dying because of you. If you’re wondering what Naomi got for herself in this, that’s it. No other ulterior motives.”

“Then make her leave,” Castiel demanded. And the moment he said it, Naomi took off as if she had been itching for a way out but dared not interrupt Castiel and Michael from talking.

“Now, if there’s no other concern, can we start?”

“Make it quick,” Cas answered, hiding his blade but kept his guard. He was too tensed when Michael handed him a piece of paper and unceremoniously cut his own wrist to bleed his grace for Castiel. Then when the grace touched Castiel’s lips, he witnessed from the archangel the creation of earth and humanity, and he marveled at the power that coursed through his veins and swept up his wings. With that much potential, it felt like everything was only an illusion as if time, soul, and grace were all one and same.

**Notes for the Chapter:**

> Ever wondered what would happen if Cas killed an archangel but took his grace? Can Cas become an archangel? Probably not but I still wanna see him that juiced up.


End file.
